When I use C, it's typically for performance reasons. I need to do funny things with pointers and bit-wise arithmetic that I can't do in higher-level languages

When I use C, it's typically for performance reasons. I need to do funny things with pointers and bit-wise arithmetic that I can't do in higher-level languages because I'm operating in cases where a few more instructions per loop iteration matter. I usually end up re-implementing very fast, cut-down versions of data structures that work only on a tightly-bounded input set for maximum performance (e.g. very fast hash table for IP addresses recently). This approach doesn't work for the cases where C really shines.